David Forbes Martyn 1906-1970

David Forbes Martyn
was born on 27 June, 1906, at Cambuslang, Scotland, the son of
Dr. Somerville Martyn. He was educated at Plymouth College and
Allan Glen's School before entering the Royal College of Science
in London. He graduated BSc, ARCSc, in 1926, obtained his PhD
from that institution in 1929, and the DSc in 1936. The great
depression was on its way when he graduated and research posts
were very difficult to obtain.

The Australian Council for Scientific and Industrial Research
(CSIR) had concentrated its work from its inception in fields
of importance to the primary industries, since the export of wool,
wheat and some other products of the land,earned virtually the
whole of Australia's overseas income. It was surprising, therefore,
that John Madsen, Professor
of Electrical Engineering in the University of Sydney, was able
to persuade CSIR to establish research in radio, through a Radio
Research Board modelled on the British body with the same name,
as the first departure from its original policy. His proposals
were put forward in 1926. Following a conference and ministerial
approval, the Australian Radio Research Board was established
in 1927, and after the squabbles inevitable at that time, it set
to work, with Madsen as Chairman, and a sum of £2,250 included
in CSIR's estimates for 1927-29 for radio research. David Martyn
was among the first four research officers appointed by the Board,
with a salary of £450 p.a.

Research Activities

Before leaving Britain for Australia, Martyn worked on the stability
of the triode oscillator, publishing three papers on this problem.
He also developed a new method for measuring extremely small alternating
currents. Upon arrival in Australia he submitted to the Radio
Research Board two detailed proposals for his work. The first
was that an attempt should be made to observe the reflection of
very high frequency radio waves from the moon; the second was
the suggestion that Appleton's frequency-change method of studying
the ionosphere might be modified by transmitting continuous saw-tooth
shaped frequency sweeps. The Board arranged for him to work in
the Physics Department of the University of Melbourne, with Professor T.H. Laby,
but after a year he joined other members of the Board's staff
in Sydney. His second proposed project has been approved by the
Board and was developed there. He soon discovered that it involved
a subtle fallacy, and abandoned it to concentrate on echo-pulse
sounding techniques. However, this abortive investigation proved
important for the subsequent development of radar in the United
Kingdom (see section on wartime activities).

In 1934 Martyn collaborated with V.A. Bailey
in a theoretical explanation of the newly discovered 'Luxembourg
Effect', where, under certain conditions, the modulation of one
radio wave becomes imposed on that of another. They showed that
this was due to a non-linear effect in the ionosphere. This explanation
of the "interaction of radio waves" was quickly accepted
and their paper on the subject is now classical.

In 1935 Martyn collaborated with A.L. Green
in a paper which showed that the effective reflection point of
radio waves in the ionosphere sometimes moved quite rapidly. This
appears to be the first discovery of moving disturbances in the
ionosphere, a topic on which a large literature now exists. In
that same year he developed a theorem relating equivalent height
and reflection coefficient at oblique incidence to that at vertical
incidence. This is now known as "Martyn's Theorem" .

This work was concerned with various aspects of the propagation
of radio waves via the ionosphere, an understanding of which is
essential for the provision of a satisfactory country-wide broadcast
system. In this he worked in close collaboration with the Postmaster
General's research staff responsible for such broadcasting. The
study involved fading and its causes and remedies, and included
measurements of the polarization of the downcoming waves and how
this might be utilized, in conjunction with a complex receiving
antenna system, to improve reception.

He also widened the scope of his researches beyond the ionosphere
to the study of all properties of the upper atmosphere above the
stratosphere. Prior to that date the generally current view of
the highest part of the atmosphere was that it consisted of hydrogen,
and was very cold and still. There was however, evidence (from
sound-ranging and meteor studies) that there might be a region
at about 50 km that was slightly warmer than the stratosphere.
In a now classical paper ('The temperatures and constituents of
the upper atmosphere') communicated to the Royal Society of London
by Lord Rutherford, the revolutionary views were put forward:

that there must be a second still colder stratosphere at about
80 km - the coldest region in the whole atmosphere;

that above 80 km the temperature rose steadily to values of
the order of l000°C;

that the atmosphere at heights of up to at least 300 km consisted
mainly of nitrogen, with a substantial proportion of oxygen;

that these upper regions were not still, but were subject
to high velocity winds and turbulence.

This paper, which was highly commended by Rutherford, aroused
vigorous discussion when read at the Royal Society.

All the conclusions mentioned above have been substantially confirmed
by later workers, notably by numerous post-War rocket and satellite
flights. It is no exaggeration to say that this paper, of itself,
transformed all subsequent thinking on almost all aspects of the
high atmosphere.

Towards the end of the War, Martyn recommenced his fundamental
researches, at Mount Stromlo Observatory, Canberra, opening up
the study of solar tidal effects in all regions of the ionosphere,
and of lunar effects in the upper (F2) region. This work comprised,
in the first place, a detailed statistical analysis of an enormous
body of data in the form of equivalent heights of the ionospheric
layers. The results were the magnitudes and phases of the tidal
effects in the various layers which, for the first time, were
accurately determined. These were later related by Martyn and
others to the theories of tides caused by solar heating and lunar
gravitation, the outcome being a greatly improved understanding
of these effects.

Later Dr. Martyn demonstrated the great variety and importance
of electrodynamic effects in the ionosphere. It had long been
recognized that at low levels where the density and collision
frequency were relatively high, the gas could be treated as a
conducting fluid, whose passage across the field lines induces
an electric field. However, at greater altitudes, where the ion
gyro-frequencies are much greater than their collision frequencies
with neutral molecules, the ions are firmly fastened to magnetic
field lines and do not move with the neutral molecules. They are
caused to move by electric fields which are induced at the lower
levels and conducted up magnetic field lines. This bi-polar drift,
in turn, causes a drag on neutral molecules and so creates winds
at the high levels. This basic work has subsequently been confirmed
and extended to the earth's magnetosphere. Dr. Martyn also pointed
out that the magnetic equatorial anomaly (low F2 peak electron
density) was almost certainly due to electrodynamic elevation
of ionization at the magnetic equator, coupled with diffusion
down the geomagnetic force lines to latitudes on either side.
This explanation is currently accepted. Finally, these electrodynamic
investigations were adapted to the extension of the earlier work
on small-scale moving disturbances. There was an error in the
initial work in the conclusion that ion drift around a local inhomogeneity
would lead to accumulation of ionization in a particular region;
in fact it leads to a wave motion. However, this work stimulated
much further theoretical investigation, notably at the Cavendish
Laboratory, a field of activity which is now very extensive.

In 1946 Martyn noted that bursts of solar radio waves were associated
with sunspot activity. He concluded that such bursts almost certainly
emanated from sunspot regions and that they would be circularly
polarized. Accordingly he devised an experimental technique which
immediately showed that certain radio radiations from active sunspots
were circularly polarized. This discovery has opened up an entire
field of research.

Because of close contact with solar astronomers, Martyn became
aware of the structure of the corona and of its probable temperature
(1,000,000°C). He thereupon worked out the thermal radio
radiation likely to be received from the solar corona and chromosphere.
In particular he calculated that the sun would show a base thermal
radiation corresponding to l,000,000°C at metre wavelengths;
at shorter wavelengths a lower temperature running down to the
chromosphere temperature of 10,000°C; and that limb brightening
should be observed at wave lengths of 60 cm downwards. All these
predictions have been confirmed experimentally, and Martyn's work
stands, not merely as the explanation of results already found,
but as a prediction of what was eventually found experimentally.
In his paper on this subject. Martyn referred to the 'Quiet Sun',
a term chosen to indicate absence of spots on the solar surface.
This term has now passed into international usage, as for instance
the IQSY, the International Years of the Quiet Sun (1964 - 1965).

In 1882 Balfour Stewart suggested that the diurnal geomagnetic
variations were due to electric currents in the upper atmosphere,
produced by the dynamo action of solar tidal winds in a conducting
region in the presence of a magnetic field. Subsequent calculations
by Schuster, Chapman and Cowling had apparently shown that the
conductivity of the ionosphere was inadequate to account for the
necessary currents. In 1948 Martyn suggested that the necessary
conductivity was present if account was taken of the Hall effect.
In 1953 he worked this out in detail in collaboration with W.G. Baker,
and established that the world-wide conductivity of the ionosphere
was adequate to explain the diurnal geomagnetic variations, and
also that it explained the electrojet at the magnetic equator,
which he had already attributed to specially enhanced conductivity
in that region.

In later works Martyn made the first clear study of the morphology
of storm geomagnetic variations in the ionosphere, and suggested
a theory of their occurrence which is still under active investigation.

In 1956 Martyn pointed out that current rocket estimates of air
density in the high atmosphere were in conflict with those derived
from observations of ionic diffusion at the 300 km level. He drew
attention again to this matter in a talk before H.R.H. the Duke
of Edinburgh in a symposium held by the Royal Society of Victoria
on 3 December,1956. In October, 1957, the first sputnik was launched;
it came to earth in a time consistent with Martyn's calculations;
upper atmosphere densities have since been revised by a factor
of 14.

Martyn established the Upper Atmosphere Section of CSIRO, in 1957,
at Camden, New South Wales.

Wartime Activities

In early 1939, following political negotiations with Britain about
the newly developed techniques of radar, Martyn was chosen to
follow up with a more technical study. He found that the secret
radar work being developed under Sir Robert Watson Watt was using
pulse techniques. On the other hand, the Royal Aircraft Establishment
(Farnborough), with Sir Edward Appleton's support, was pressing
an alternative development using continuous frequency change,
and there was serious argument whether a substantial part of the
country's effort should not be diverted to this alternative, which
appeared likely to be more efficient. The files on the matter
were shown to Martyn, who recognized at once that the latter involved
the fallacy which he had himself found earlier in the decade,
but had not published. Watson Watt and Appleton accepted his reasoning
immediately, and no further attempt was made to divert a part
of Britain's defence effort into this channel. He returned to
Australia in August, 1939, reporting en route to the Cabinet of
the New Zealand Government upon these secret developments.

Shortly after reaching Australia, he reported to the wartime Cabinet.
Very rapid agreement was reached that CSIR should set up a Division
of Radiophysics, with Martyn as its Chief.

A Radiophysics Laboratory was established just before the outbreak
of war in an enlarged part of the Standards Laboratory, situated
in the grounds of the University of Sydney. Its earliest members,
later to become group leaders, were J.H. Piddington
(radar systems design), J.L. Pawsey
(basic research), H.J. Brown (laboratory services). The initial
efforts were directed towards adapting British equipment to use
in Australia, but it was soon realized that this equipment was
quite unsuitable for conditions here. The first new system designed
was called Shore Defence Radar, for detecting and accurately locating
surface vessels. This system was successfully integrated with
the 9.2 inch and 6 inch coast defence guns, and although these
played little part in the war, the day and night warning system
was important as insurance. Its qualities were recognized by the
British Army, and units were ordered to be sited in Malaya, Hong
Kong and Burma. Fortunately the equipment had not been delivered
when these areas fell to the Japanese.

An important aspect of the Shore Defence set was its provision
of a basic design framework for the Air Warning Radar. The necessity
for such equipment was realized immediately following Japan's
entry into the war, and a unit was designed, built, and put into
operation within a week. This particular set provided Sydney with
its only air warning system for some nine months, although by
that time Martyn had left Radiophysics.

A major difficulty in the use of radar by the armed forces was
the development of adequate liaison between the designers and
the users. Martyn recognized this difficulty and spent a great
deal of time travelling to radar sites, lecturing to groups of
officers and developing close contacts. Of these, the earliest
and most fruitful was with Colonel (later Major-General) J.S.
Whitelaw, who was largely responsible for the early introduction
of radar into the armed services, and who became a close personal
friend of Martyn.

In 1942, for reasons which are not now clear, Martyn was replaced
by F.W.G. White as Chief
of the Division of Radiophysics. This action affected Martyn profoundly.
It left him with bitterness which became, at times, an obsession,
and it coloured both personal and institutional relationships.
It did not, however, reduce his desire to contribute, as fully
as he could, to the war effort. He left the Division of Radiophysics
in June, 1942, to direct an Operational Research Group for the
armed services.

The group was restricted to weapon research in general, and radar
in particular. It was not concerned with design and maintenance
of radar, but with the scientific principles involved in its efficient
operational use. The major activity of group was an investigation
of the effects of severe atmospheric refraction of radio waves
and the consequent malfunctioning of radar sets. These studies
led to a general improvement in the operational efficiency of
radar, particularly along the northern coast of Australian

Influence on Australian Science

In the 1930's, Australian physics had fallen into a backwater.
Martyn and Pulley's paper ('The temperatures and constituents
of the upper atmosphere') redirected world attention to physics
in Australia. In particular, in 1936 Professor T.H. Laby, FRS,
brought out to Australia Professor H.S.W. Massey,
his former pupil, to study the implications of the new discoveries.
Sir Harrie Massey, FRS, has since followed up these matters assiduously,
and is now known internationally for his upper atmosphere and
space research activities.

In 1950, because of his work on radio-emission from the sun, Martyn
was recognized throughout the world as a leader in radio astronomy,
and in consequence was elected at Zurich as President of the newly
formed Radio Astronomy Commission of the International Union of
Radio Science (URSI). He promptly invited URSI to hold its next
General Assembly in Australia, although the necessary finance
had not yet been obtained. Eventually this bold attempt achieved
the necessary financial backing from the Commonwealth Treasury
and Australian industry, and URSI held its next General Assembly
in Australia, in 1952, the first time that any international scientific
union met south of the Equator. This meeting showed the scientific
world how far advanced Australia was, not only in ionospheric
research, but also in radio astronomy.

At this time, discussions between CSIRO and the Department of
the Interior resulted in an understanding that the Mount Stromlo
Observatory would no longer pursue radio astronomical studies,
to avoid duplication of effort with the Radiophysics Division
of CSIRO. In consequence, Martyn reverted to ionospheric research,
and after four years as President of URSI's Radio Astronomy Commission,
was elected to a four year term as President of the Ionospheric
Commission of URSI.

Martyn spent much effort in preliminary organization of Australia's
activities in the International Geophysical Year, and in securing
funds for this notable enterprise

In 1959 the Australian Broadcasting Commission inaugurated an
annual series of ABC lectures, which 'A prominent member of the
Australian community would be invited to present the results of
his work and thinking on one of society's major problems.' Dr.
Martyn was invited to give the first of these lectures. He chose
as his topic 'Society in the Space Age', a series of four lectures
which has been published and recently re-printed by the ABC.

International Activities

Mention has already been made of Martyn's Presidencies within
URSI. In 1962 he was invited by the United Nations (following
agreement between the US and USSR) to be Chairman of that body's
Scientific and Technical Sub-Committee of the Committee on the
Peaceful Uses of Outer Space. (This Committee is attended by the
leading space scientists of 28 nations.) The Committee is also
enjoined to achieve its objectives by unanimous consent. It has
provided unanimously agreed reports on such matters as contamination
of outer space, and has also set up an international research
rocket range in South India. It is unique to have Australia chairing
a UN Committee for a decade. This is due both to Dr Martyn's scientific
eminence, and to his tact and impartiality in dealing with countries
from the so-called West, East, and unaligned regions.

Dr Martyn was also elected for a four year term to the Executive
Committee of the International Couneil of Scientific Unions (ICSU),
the body controlling the activities of all international scientific
unions and the joint activities of groups of unions. It is known
that he was nominated by several countries for the Presidency
of ICSU, however, he refused these nominations, stating that at
the present time he considered that the President of ICSU should
reside closer to the current centre of gravity of international
scientific activities.

Dr Martyn was editor (for the Southern Hemisphere) of the international
journal Planetary and Space Science; he was also on the
Board of Editors of Space Science Reviews, and a member
of the Board of Trustees of the International Astronautical Federation.

During the last three years of his life, Martyn became increasingly
concerned with problems of conservation of the biosphere as the
milieu of all life of which there is knowledge. The importance
of action to preserve what remained of 'natural' environment for
wild flora and fauna, and to counter man's senseless and increasing
contamination of the atmosphere, the waterways and even the sea,
was brought home to him through international discussion of the
contaminants which space-vehicles could carry to other planets
and the moon. As he became aware of the nature and scale of man's
spoilation and destruction of his own environment, and encountered
apathy and distrust in officials of government and industry towards
measures of control, he began to feel that little or nothing could
be done to avert ultimate disaster. This was not characteristic
of Martyn, for he was ever a fighter for any cause in which he
became deeply involved, and it clearly contributed to the despondent
mood which overcame him in the end.

The high esteem in which Martyn was held in the international
field is reflected in the numerous letters and telegrams received
by his widow. The Minister for External Affairs stressed how highly
his Department valued its association with Martyn, which began
on his election as Chairman of the Scientific and Technical Sub-Committee
of the U N Committee in 1962. He added that Martyn did a great
deal to advance Australia's standing in the United Nations, and
that many officers of his Department remembered him with affection
and with gratitude for the help and advice he gave them. The Minister
for Education and Science wrote of his high opinion of Martyn
and his feeling of a personal sense of loss. The Secretary-General
of the United Nations wrote to the Australian Permanent Representative
of the United Nations of Martyn's pursuit of the goal of international
co-operation with devotion and scholarship, and added that his
contribution within the United Nations and several international
scientific organizations will long be remembered.

Honours

Martyn was elected a Fellow of the Royal Society of London in
1950, the first such election of a physicist in Australia for
twenty years. He was awarded the Lyle Medal of the Australian
National Research Council, and the Sidey Medal of the Royal Society
of New Zealand, both in 1947. In 1950 he received the Burfitt
Medal of the Royal Society of N.S.W., and in 1954 the Charles
Chree Medal of the Physical Society of London.

The Australian Academy of Science

In 1951, as part of the celebrations of the fiftieth anniversay
of Federation, the Australian National University organized a
seminar on Science in Australia. Sir Edward Mellanby, Secretary
of the Medical Research Council in UK, and Dr J.B. Conant, President
of Harvard, with prominent Australian representatives of industry
and science, took part in a comprehensive discussion of the state
and role of science in the Commonwealth. The seminar emphasized
the need for an Australian society of scientists of distinction;
to serve as the body adhering to the international unions, and
represent Australian science generally, both nationally and internationally;
to bring the scattered scientific efforts of the Commonwealth
together; to conduct seminars and conferences; to offer advice
to the Government on questions concerning the welfare of science
in Australia; and generally to promote and disseminate scientific
knowledge. Martyn took part in the discussion, and subsequently
he and Oliphant considered how an Australian Academy of Science,
the constitution and objectives of which should be based on those
of the corresponding body in Britain, the Royal Society of London,
might be brought into existence. They considered the factors which
has rendered abortive several previous attempts to found a society
of this kind, and concluded that interstate jealousies and personal
difficulties were responsible. They decided that as the twelve
Fellows of the Royal Society resident in Australia has been elected
by an outside, disinterested institution, there would be less
objection to an attempt by them to establish a new society at
high level. Eleven agreed to co-operate. One, who was elderly
and an invalid, disillusioned by previous experience, said that
he did not wish to be associated with yet another failure.

The Australian National Research Council, with wide membership,
was the adhering body to the international scientific unions at
that time. It was necessary to obtain its agreement to hand over
these responsibilities to the proposed Academy. In the delicate
negotiations which ensued, Martyn displayed remarkable statesmanship.
He was never impatient, and showed great understanding of the
feelings and attitudes of the officers and members of ANRC. It
was largely Martyn's persistent advocacy which persuaded that
body to co-operate and hand over all its responsibilities to the
Academy.

So that it was more representative of science generally, the Fellows
of the Royal Society invited 25 distinguished Australian scientists
to join with them as Foundation Fellows of the Academy. In this
task Martyn showed sound judgment, and worked to ensure that these
men were as widely distributed, geographically, as the standards
adopted would allow. The enlarged group then drew up and adopted
statutes and rules. With the help of Mr. Norman Cowper (later
Sir Norman), who had agreed to serve as honorary solicitor to
the group, Martyn cast these into acceptable forms, spending much
time and great effort to ensure that they correctly interpreted
the wishes of the membership and the needs of the law. On the
basis of these documents, and with the willing co-operation of
the Royal Society of London and of the Prime Minister, application
was made for a Royal Charter. This was granted in the record time
of three weeks, so that Queen Elizabeth II was able to present
it to the Interim President and officers, at Government House,
Canberra on 16 February, 1954. Thus, largely owing to the continued
effort of D.F. Martyn, the Australian Academy of Science came
into being. He was the first Secretary (Physical Sciences). The
Commonwealth Government agreed to provide an annual subvention,
following an interview which the Prime Minister granted to the
President and Sir David Rivett, on the basis of estimates for
which Martyn was largely responsible.

Martyn was elected President of the Academy in 1969 in succession
to Sir Macfarlane Burnet,
and held that office when he died. Meanwhile, he had continued
to serve the Academy on various committees, and always played
a prominent party in the Annual General Meetings. He was truly
committed to maintenance of the standards of the Fellowship, and
to the part the Academy could play to promote Australian science,
at home and in its international relations.

Personal

The standards which Martyn expected in scientific research were
high and when work which he regarded as wrong was submitted for
any purpose, or published, his judgement could be harsh. But he
gave full acknowledgment of good work, and pressed strongly the
claims for election to the Academy, or for the award of a prize,
by men of science whose work he approved. If he had a model of
a scientist of distinction, it was Sydney Chapman,
whose opinion he valued above all.

Martyn never gathered round him a large group of collaborators.
In essence he was a theoretician, preferring to work quietly and
alone on problems which interested him, and at his own pace. Yet,
it is clear from his notable success in international scientific
bodies that he was a gifted chairman of meetings, who could be
tactful, yet firm. This attribute was particularly apparent in
the foundation of the Australian Academy of Science. There were
occasions when obstruction, and the desire to reduce standards
for Fellowship, threatened collapse of the proposal to establish
an Academy. It was then that Martyn's persistence, powers of persuasion
and great tact, prevented disaster, without relaxing in any way
the high objectives of the founding group.

Martyn was a trout fisherman of great skill, and a connoisseur
of food and wine. On social occasions he was a man of charm and
good conversation. He will be missed greatly by all who won his
warm friendship. In 1944 he married Margot Adams of Sydney. They
had no children.

John Hobart Piddington,
PhD, is Senior Principal Research Scientist, Division of Physics,
CSIRO, Chippendale, Sydney, NSW. He was elected a Fellow of the
Academy in 1963.

Sir Mark Laurence Elwin Oliphant,
KBE, D Sc, FRS, is Emeritus Professor, Research School of Physical
Sciences, Australian National University, Canberra. He is a Foundation
Fellow.

This memoir was originally published in Records of the Australian
Academy of Science, vol. 2, no. 2, Canberra, Australia,
1971.